in general, the left hemisphere excels in intellectual, rational, verbal, and analytical thinking and the right hemisphere excels in emotional, non-verbal, and intuitive thinking

axon collaterals

arise from Nodes of Ranvier, projecting to many different areas or nuclei

decussate

With few exceptions, pathways in the brain do this (cross), such that each hemisphere of the brain controls (or processes information from) the opposite side of the body. Different pathways decussate in different areas of the brain

“project to”

A nucleus is said to do this another nucleus or area. always used to mean "innervates directly "; thus the motor cortex does not do this to the muscle

“descending or ascending” axons

“relative” terms used generally for pathways going in the direction “away from or to” the cortex

corticospinal tract

tract in which axonstravel all the way from the motor cortex where their cell bodies lie to the appropriate spinal cord level they innervate; the corticospinal tract is an example of a descending pathway; damage anywhere along the pathway (or in the motor cortex or spinal cord) will produce motor signs/symptoms

1 cerebral cortex ("bark", as in the bark of a tree) or mantle of gray matter,
3 A core of subcortical "white" matter,
4 Deep in the interior of each cerebral hemisphere is a lateral ventricle (a "C"-shaped cavity in each hemisphere where most of the CSF is made),
5 and subcortical nuclei referred to as the basal ganglia (including the corpus striatum, amygdala, claustrum, nucleus basalis of Meynert [substantia innominata])

gyri

folds of cortex are called this

sulci

the grooves between the gyri

fissure

if a sulcus is very deep, it may be called this

term for agyric cortices;

lissencephalic (from the Greek meaning "smooth brain")

effects of cortical degenerative disease on gyri and sulci, and ventricles

cortical neurons die and gyri become smaller and the sulci between the gyri enlarge, ventricles dilate

axons of cortical neurons which leave the cortex to synapse in other subcortical areas; axons of cells lying in subcortical structures which project to the cortex

Commissural fibers

axons of cortical cells which cross the midline to connect the two hemispheres

corpus callosum

the most important commissural pathway

anterior and posterior commissures

two minor commissural pathways

Association fibers

axons of cortical cells which connect different functional areas within the same hemisphere

lateral ventricle

"C"-shaped cavity in each hemisphere where most of the CSF is made, deep in the interior of each cerebral hemisphere

basal ganglia

subcortical nuclei deep in the interior of each cerebral hemisphere

Diencephalon location

Anatomically, this area of the brain is located in each hemisphere lateral to the third ventricle

hypothalamic sulcus significance

the diencephalon is divided into two areas by this groove

Components of the Diencephalon

Dorsally, the thalamus ("anteroom"), Ventrally, the hypothalamus

thalamus

all information destined for the cortex must be relayed (via a synapse) through this structure

hypothalamus

he general function of this structure is as a CNS center for the regulation of autonomic and endocrine functions to maintain internal homeostasis; also a major player in the limbic system (emotions)

Mesencephalon (midbrain), general location and major divisions

This General area of the brain that fits through the tentorial incisure or notch, Divided by the cerebral aqueduct of Sylvius into a "tectum" (roof) [contains superior and inferior colliculi] and a "tegmentum" (floor)

tectum location

part of midbrain superior to cerebral aqueduct of sylvius

tegmentum

part of midbrain inferior to cerebral aqueduct of sylvius

divisions of textum

superior and inferior colliculi

superior and inferior colliculus function

involved in visual and auditory reflexes, respectively; in non-mammalian vertebrates, the "optic tectum" is the major visual structure in the brain and is the homolog of the mammalian superior colliculus

tegmentum function

Most of the pathways coming down from higher structures on their way below the midbrain, and fibers from below on their way to higher levels of the brain, course in this structure

substantia nigra, location, claim to fame

the nucleus in the midbrain which degenerates in Parkinson's Syndrome)

Metencephalon (means "between" brain) components

Cerebellum and pons (“bridge”)

Cerebellum ("little cerebrum") function

a structure primarily concerned with integrating sensory information to allow for a coordinated motor response; plays a role in the proper "timing" and coordination of learned, skilled motor movement; also involved in some forms of cognitive learning

folia

folds of cerebellar cortex

components of cerebellum

1 two hemispheres,
2 cortex (folds of cerebellar cortex are called folia, not gyri; grooves between the folia are called fissures),
3 underlying white matter,
4 deep nuclei.
5 midline structure called the vermis,
6 rounded lobule on the undersurface of each hemisphere continuous with the vermis called a tonsil

vermis

midline structure in cerebellum

tonsil (CNS)

rounded lobule on the undersurface of each cerebellar hemisphere continues with the vermis. herniates thru foramen magnum in tonsillar herniation

1) Long pathways course through this structure//
2) has portion of the reticular formation; nuclei involved in vital functions; in tonsillar herniation tonsil of the cerebellum presses down//
3) is continuous with spinal cord at foramen magnum //
4) many motor nuclei of cranial nerves located here, the pathways from cortex to these nuclei are referred to as the cortico-bulbar pathway

reticular formation

it is in this area that nuclei involved in vital functions such as consciousness, heart-rate and rhythm, breathing, etc. are located;

cortico-bulbar

Because many motor nuclei of the cranial nerves are located in the medulla, the pathways from the cortex to these nuclei are referred to as this

Subdivisions of CNS

Forebrain, midbrain, hindbrain, brainstem

forebrain

this would include the cerebrum (cerebral cortex and deep nuclei of the telencephalon) and the diencephalons

divides the two hemispheres; the falx cerebri fits down into this fissure to the level of the corpus callosum

Lateral or Sylvian fissure:

fissure located laterally on the surface of the cortex

Central sulcus or sulcus of Rolando

sulcus that begins slightly behind the midpoint of the brain and generally descends with a forward inclination

Parieto-occipital sulcus

sulcus located primarily on the medial surface of the hemisphere about 4-5 cm in front of the occipital pole; it is reflected for only a short distance over the superior border of the hemisphere on the lateral surface

Lobes of the cerebral cortex

Frontal lobe, Parietal lobe, Occipital lobe, Temporal lobe

Frontal lobe demarcations

demarcated by the Sylvian fissure below and the central sulcus of Rolondo caudally

axons of cortical cells in this area make up part of the corticospinal tract, a very important pathway in man necessary for the initiation of voluntary motor movement, somatotopically organized

The precentral gyrus also called the "primary" motor cortex (Area 4)

Superior and inferior frontal sulci structure and location

located at right angles to the precentral gyrus; these sulci of the frontal lobe form the borders of three gyri: the superior, middle and inferior frontal gyri

structure of the inferior frontal gyrus

Ascending rami of the lateral fissure divide this gyrus into three smaller areas: the pars orbitalis, pars triangularis, and pars opercularis; the posterior part consisting of the pars triangularis and pars operularis (Areas 45 and 44)

In the dominant hemisphere (usually the left hemisphere), Areas 44 and 45 (also called Broca's Area) function

brain regions critically involved in the motor control of language

Damage to or compromise of the blood supply to Broca's area results

damage to this area results in an individual who can understand spoken language, but has difficulty in speaking language fluently; if severe enough, the person will become mute

aphasia

cquired disorders of language are referred to as this

Prefrontal cortex location

anterior-most part of the frontal lobes (rostral to Areas 6 and 8; made up of a number of distinct areas);

is entirely within the frontal lobe; believed to play a role in some aspects of cognitive and motor behavior; Broca’s area is generally considered part of this

Limbic association cortex

Areas of the prefrontal cortex, in particular, appear to be critically involved in the abstraction of cultural mores, rules of social interaction, judgment, and the ability to perceive and to reflect on the consequences of one's actions; other specific areas in the prefrontal cortex play a role in appropriately associating “affect” with “experience”; these areas are linked to the most complex intellectual functions and imagination

Prefrontal lobotomy

removal of the prefrontal lobes

leukotomy

cutting of the axons beneath the prefrontal area

There is also lateralization of function in the limbic cortex

serious depression occurs more often following left frontal lobe lesions; mania occurs more often from right frontal lobe lesions

Parietal lobe demarcations

demarcated anteriorly by the central sulcus of Rolando, inferiorly by the lateral fissure, and posteriorly by an imaginary line extending from the parieto-occipital sulcus to the top of the Sylvian fissure

each point on the retina represented in this area so that a "map" of visual space (retina) is represented in the brain; again, there is a disproportionate representation, with the greatest cortical area being devoted to macular or central vision

the individual is not blind, but cannot recognize an object or its “significance” by sight alone, produced by lesions of the visual association areas

Temporal lobe demarcations

demarcated by the Sylvian fissure dorsally and the parieto-occipital sulcus/preoccipital notch "line" caudally

major sulci and gyri of temporal lobe

Superior and inferior temporal sulci,

Superior and inferior temporal sulci location, structure

sulci which run parallel with the Sylvian fissure and divide the temporal lobe into three major gyri: the superior, middle, and inferior temporal gyri

transverse temporal gyri of Heschl, location importance

gyrus on the superior aspect of the superior temporal gyrus where Area 41 is located; this area constitutes the "primary" auditory cortex

unilateral lesions of primary auditory cortex results

lesions of this area do not produce deafness; rather the individual will show a bilateral diminution in hearing, with a greater loss contralaterally, and some difficulty in the localization of the source of sounds contralaterally; bilateral lesions this area, which would be extremely rare, would produce deafness

higher order auditory areas example, location, lesion results

these areas (for example, Area 42) also surround the primary auditory cortex; because of the bilaterality of auditory connections, lesions in these areas do not generally produce auditory agnosias

Wernicke's Area

Area 22: this area is necessary for the interpretation of spoken language; individuals with lesions in this area cannot understand spoken language and said to have or receptive aphasia. such patients speak language fluently, but what they say is nonsense; because this area is very close to other language areas in the parietal lobe (the supramarginal and angular gyri), patients may also have problems with written language functions as well; patients may become increasingly paranoid over time

prosopagnosia, cause

inability to match a “face” with an “identity”, caused by lesions of the temporal lobe

constitutes primary somatosensory cortex: important for apprectiation of pain, temperature, pressure, touch, and propioception. has a somatotopic organization similar and parallel to the representation in motor cortex, with the face represented on the inferior lateral surface and the leg represented over the dorsal ridge or crown on the medial surface

Intraparietal sulcus location

at right angles and posterior to the postcentral gyrus; between the superior parietal lobule and the inferior parietal lobule

somatosensory agnosias

condition where the individual cannot recognize something on the basis of touch alone

Result of lesion of Part of the postcentral gyrus (part of Area 2) and part of the superior parietal lobule (Area 5) [somatosensory association areas ]

somatosensory agnosia is a result of lesions in these locations

Areas 5 and 7 function

posterior parietal cortex); these areas are believed to play a major role in coordinating visual and somatosensory information

inferior parietal lobule component gyri

the supramarginal (Area 40) and angular gyri (Area 39) comprise this area

supramarginal (Area 40) and angular gyri (Area 39) function

these two gyri are important for the perception and interpretation primarily of written language – and also for sight-reading of music

result of lesions of Areas 39 and 40

patients with lesions here in the dominant hemisphere have aphasias characterized by difficulties in reading (called alexia) and writing (called agraphia)

what is amygdala

subcortical nucleus in temporal pole of brain

what is lateral geniculate nucleus

nucleus located in the thalamus which recieves input from parts of both eyes and projects to a number of other ares, including primary visual cortex (area 17)

what is medial geniculate nucleus

nucleus located in thalamus which receives input from the inferior colliculus and projects to structures involved in the processing of auditory inforation, including primary auditory cortex (area 41)

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